A typical liquid crystal display is capable of displaying a clear and sharp image through millions of pixels that make up the complete image. The liquid crystal display has thus been applied to various electronic equipment in which messages or pictures need to be displayed, such as mobile phones and notebook computers. However, liquid crystals in the liquid crystal display do not themselves emit light. Rather, the liquid crystals have to be lit up by a light source so as to clearly and sharply display text and images. The light source may be ambient light, or a backlight module attached to the liquid crystal display.
Referring to FIG. 6, a conventional backlight module 1 generally includes a light source 11, a reflective plate 12, a light guide plate 13, a diffusing plate 14, and a brightness enhancement plate 15. The reflective plate 12, the light guide plate 13, the diffusing plate 14, and the brightness enhancement plate 15 are arranged in that order from bottom to top. The light source 11 is positioned adjacent to a side edge of the light guide plate 13.
After light beams from the light source 11 enter the light guide plate 13, the light beams emit out from a top surface of the light guide plate 13 and enter the diffusing plate 14. The light beams are diffused to be uniform, and then enter the brightness enhancement plate 15. When emitting out from the brightness enhancement plate 15, the light beams are focused in a predetermined range of angles. Thus the light beams emitted from the backlight module 1 are uniform and have a high brightness.
However, in order to make the emitting light beams uniform, the backlight module 1 needs the diffusing plate 14. This adds to a thickness of the backlight module 1, makes assembly of the backlight module 1 relatively complicated, and makes the backlight module 1 unduly costly.
Therefore, a new light guide plate and a corresponding backlight module that can overcome the above-described problems are desired.